feat(dns-server): Improve DNS server interface binding by adding explicit IP validation, configurable UDP/HTTPS binding, and enhanced logging.

readme.md

@@ -190,6 +190,17 @@ const dnsServer = new DnsServer({
   dnssecZone: 'example.com'      // Optional: enable DNSSEC for this zone
 });
 
+// For enhanced security, bind to specific interfaces
+const secureServer = new DnsServer({
+  udpPort: 53,
+  httpsPort: 443,
+  httpsKey: 'path/to/key.pem',
+  httpsCert: 'path/to/cert.pem',
+  dnssecZone: 'example.com',
+  udpBindInterface: '127.0.0.1',    // Bind UDP to localhost only
+  httpsBindInterface: '127.0.0.1'   // Bind HTTPS to localhost only
+});
+
 // Register a handler for all subdomains of example.com
 dnsServer.registerHandler('*.example.com', ['A'], (question) => ({
   name: question.name,
@@ -363,6 +374,56 @@ await dnsServer.start();
 //      https://localhost:8443/dns-query
 ```
 
+### Interface Binding
+
+For enhanced security and network isolation, you can bind the DNS server to specific network interfaces instead of all available interfaces.
+
+#### Localhost-Only Binding
+
+Bind to localhost for development or local-only DNS services:
+
+```typescript
+const localServer = new DnsServer({
+  udpPort: 5353,
+  httpsPort: 8443,
+  httpsKey: cert.key,
+  httpsCert: cert.cert,
+  dnssecZone: 'local.test',
+  udpBindInterface: '127.0.0.1',     // IPv4 localhost
+  httpsBindInterface: '127.0.0.1'
+});
+
+// Or use IPv6 localhost
+const ipv6LocalServer = new DnsServer({
+  // ... other options
+  udpBindInterface: '::1',           // IPv6 localhost
+  httpsBindInterface: '::1'
+});
+```
+
+#### Specific Interface Binding
+
+Bind to a specific network interface in multi-homed servers:
+
+```typescript
+const interfaceServer = new DnsServer({
+  udpPort: 53,
+  httpsPort: 443,
+  httpsKey: cert.key,
+  httpsCert: cert.cert,
+  dnssecZone: 'example.com',
+  udpBindInterface: '192.168.1.100',  // Specific internal interface
+  httpsBindInterface: '10.0.0.50'    // Different interface for HTTPS
+});
+```
+
+#### Security Considerations
+
+- **Default Behavior**: If not specified, servers bind to all interfaces (`0.0.0.0`)
+- **Localhost Binding**: Use `127.0.0.1` or `::1` for development and testing
+- **Production**: Consider binding to specific internal interfaces for security
+- **Validation**: Invalid IP addresses will throw an error during server startup
+
 ### Advanced Handler Patterns
 
 #### Pattern-Based Routing